U.S. patent number 6,818,845 [Application Number 09/964,940] was granted by the patent office on 2004-11-16 for electromechanical switch.
This patent grant is currently assigned to Phonak AG. Invention is credited to Paul Portmann.
United States Patent |
6,818,845 |
Portmann |
November 16, 2004 |
Electromechanical switch
Abstract
The switching element (1) of the switch per this invention is
closely enveloped, at least in the area of its free end, by an
elastic diaphragm (5) which also encloses, at a distance, the
contact surfaces (2) facing the switching element (1) and which is
tightly connected to the switch housing (4; 6). This tightly seals
the contact region against the external environment of the switch
and thus reliably prevents contamination and oxidation of the
contact surfaces. As another advantageous feature, the number of
switch components is thus reduced, a mechanical spring is not
needed for retaining the switching element (1) in its engaged
position, and the design permits miniaturization.
Inventors: |
Portmann; Paul (Schindellegi,
CH) |
Assignee: |
Phonak AG (Stafa,
CH)
|
Family
ID: |
25705686 |
Appl.
No.: |
09/964,940 |
Filed: |
September 27, 2001 |
Current U.S.
Class: |
200/302.3;
200/339; 200/553 |
Current CPC
Class: |
H01H
23/06 (20130101); H01H 2300/004 (20130101); H01H
2009/048 (20130101); H01H 23/146 (20130101) |
Current International
Class: |
H01H
23/06 (20060101); H01H 23/00 (20060101); H01H
23/14 (20060101); H01H 023/00 () |
Field of
Search: |
;200/302.3,339,302.1,302.2,512,513,517,553,562,438,406,250,260,557,333 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Luebke; Renee
Attorney, Agent or Firm: Pearne & Gordon LLP
Claims
What is claimed is:
1. An electromechanical switch incorporating in a switch housing at
least one electrically conductive switching element (1) with
associated electrically conductive contact surfaces (2), wherein an
area of the switching element (1) that faces away from the contact
surfaces is at least partly enclosed by an elastic diaphragm (5)
which also encloses at least a region containing the contact
surfaces (2) associated with the switching element (1) and tightly
butts against the switch housing (4; 6) wherein said diaphragm (5)
is prestressed in a transition area between the switching element
(1) and the housing (4; 6), thus resiliently pressing the switching
element (1) against the contact surfaces (2), wherein the switch
housing (4; 6) consists of two sections, with a base plate (4)
containing the contact surfaces (2) and a cover (6) with an opening
(6') through which protrudes a part of the switching element (1)
with a diaphragm (5), wherein said two housing sections (4; 6) are
connected in self-locking fashion by clamping or welding.
2. An electromechanical switch incorporating in a switch housing at
least one electrically conductive switching element (1) with
associated electrically conductive contact surfaces (2), wherein an
area of the switching element (1) that faces away from the contact
surfaces is at least partly enclosed by an elastic diaphragm (5)
which also encloses at least a region containing the contact
surfaces (2) associated with the switching element (1) and tightly
butts against the switch housing (4; 6) wherein said diaphragm (5)
is prestressed in a transition area between the switching element
(1) and the housing (4; 6), thus resiliently pressing the switching
element (1) against the contact surfaces (2), wherein the switching
element (1) is pin-shaped and has a round or oval cross section
while its end (1'), which makes contact with the contact surfaces
(2) is rounded into a convex tip.
3. An electromechanical switch incorporating in a switch housing at
least one electrically conductive switching element (1) with
associated electrically conductive contact surfaces (2), wherein an
area of the switching element (1) that faces away from the contact
surfaces is at least partly enclosed by an elastic diaphragm (5)
which also encloses at least a region containing the contact
surfaces (2) associated with the switching element (1) and tightly
butts against the switch housing (4; 6) wherein said diaphragm (5)
is prestressed in a transition area between the switching element
(1) and the housing (4; 6), thus resiliently pressing the switching
element (1) against the contact surfaces (2), wherein, in the area
where it rests against the switching element (1) and/or in the
transition area between the switching element (1) and its
connection to the switch housing (4; 6), the diaphragm (5) is
provided on its inside and/or outside with one or several notches
(7).
4. An electromechanical switch incorporating in a switch housing at
least one electrically conductive switching element (1) with
associated electrically conductive contact surfaces (2), wherein an
area of the switching element (1) that faces away from the contact
surfaces is at least partly enclosed by an elastic diaphragm (5)
which also encloses at least a region containing the contact
surfaces (2) associated with the switching element (1) and tightly
butts against the switch housing (4; 6) wherein said diaphragm (5)
is prestressed in a transition area between the switching element
(1) and the housing (4; 6), thus resiliently pressing the switching
element (1) against the contact surfaces (2), wherein the contact
surfaces (2) comprise contact pins (3) whose ends (2) facing the
switching element (1) are hemispherical or mushroom-shaped.
5. An electromechanical switch incorporating in its switch housing
at least one pin shaped, electrically conductive switching element
(1) with associated electrically conductive contact surfaces (2),
wherein an area of the switching element (1) that faces away from
the contact surfaces is at least partly enclosed by an elastic
diaphragm (5) which also encloses at least a region containing the
contact surfaces (2) associated with the switching element (1) and
tightly butts against the switch housing (4; 6) wherein said
diaphragm (5) is prestressed in a transition area between the
switching element (1) and the housing (4; 6), thus resiliently
pressing the switching element (1) against the contact surfaces (2)
to establish an electrically conductive connection between the
contact surfaces.
6. The switch according to any one of claims 1 and 5, wherein the
switching element (1) comprises a metal.
7. The switch according to any one of claims 1 and 5, wherein the
switch housing (4; 6) comprises a 2-component injection-molded
plastic material.
8. The switch according to any one of claims 1 and 5, wherein the
elastic diaphragm (5) comprises an elastomeric material.
9. Use of a switch per one of the claims 1, 2, 3, and 4 in
miniaturized devices.
10. The use of the switch according to claim 9, wherein the
miniaturized devices are hearing aids.
Description
This invention relates to an electromechanical switch.
There are a great many different electromechanical switches on the
market, designed to connect or disconnect electrical conductors.
The fundamental mechanical concept of these switches is essentially
the same, in that a movable, current-conducting switching element
presses down on appropriate contact surfaces of the conductors or
wires that connect to the switch, thus establishing the electrical
connection or, respectively, the switching element is moved away
from the contact surfaces, thus breaking the electrical connection.
The switching element generally makes simultaneous contact with two
neighboring contact surfaces, thus establishing the electrical
connection between these two contact surfaces.
The switching element is traditionally moved by means of a lever
which is contained in the same switch housing and is movably or
rigidly connected to the switching element. This lever usually
consists of an electrically nonconducting material or it is at
least safely insulated from the switching element and the contact
surfaces.
One inherent problem of this type of switches lies in the fact that
due to the clearance needed for the movement between the lever and
the switch housing it is not possible to completely seal the switch
mechanism. Dirt and moisture can penetrate into the switch housing,
soiling or oxidizing especially the contact surfaces and/or the
switching element. This can lead to a significant deterioration of
the functionality of the switch or cause it to fail altogether.
Switches which are exposed to such conditions and must therefore
meet stringent weather-proofing requirements can be provided with
additional seals which are traditionally positioned at least around
the lever and provide a water-tight connection with the switch
housing.
That is a costly solution since additional materials must be used.
It also increases the size of the box, i.e. the switches thus
equipped usually have greater dimensions. It is a solution that
does not lend itself well to switches which must be kept small.
It is therefore the objective of this invention to introduce an
electrical switch that can be produced in simple fashion and even
with very small dimensions and which would permit reliable
switching, i.e. circuit-connect and disconnect operations, while
dependably protecting the switch unit against exposure to the
effects of external moisture.
The invention meets this objective by means of an electrical switch
having novel features as described herein.
A surprising discovery has revealed the possibility of sealing the
switch mechanism with a diaphragm which at the same time and in
advantageous fashion serves to provide electrical insulation of the
free end of the switching element, which can thus function as the
actuating surface of the switch and by means of which the switching
element applies the contacting pressure on the contact surfaces. As
an added advantage, the construction of this type of
electromechanical switch is simplified insofar as separate, elastic
elements serving to ensure alignment and to produce the necessary
contact pressure, such as metal springs employed in conventional
switches, can be dispensed with.
The elastic diaphragm exerts this contact pressure preferably by
means of its defined prestressed condition between the switch
housing and the switching element. This can be accomplished, for
example, in that the diaphragm is pulled over the preferably
pin-shaped switching element and, with a small amount of tension
corresponding to the required contact pressure and skirting the
contact surfaces, it is attached to the appropriate section of the
switch housing.
Consequently, one single element advantageously meets the
mechanical requirements (contact pressure, insulation) while also
sealing the unit.
Switches of this type are especially practical for use in small
electronic devices, a particular example being hearing aids.
The following description of an implementation example explains
this invention in more detail with the aid of the drawings in
which--
FIG. 1 shows a longitudinal section through a switch according to
this invention;
FIG. 2 is a bottom view of the switch per FIG. 1;
FIG. 3 shows a longitudinal section through the switch as in FIG.
1, offset by 90.degree.;
FIG. 4 depicts the diaphragm of the switch per FIG. 1;
FIG. 5 and FIG. 6 illustrate different configurations of the
contact surfaces; and
FIG. 7 shows a longitudinal section through the switch mechanism of
another design variation of the switch per FIG. 1 with 4 contact
surfaces.
FIG. 1 shows a longitudinal section through a switch designed in
accordance with this invention, in which the pin-shaped switching
element 1 makes contact with two contact surfaces 2 of three
mutually parallel contact pins 3.
In this case, the contact pins 3 are mounted, side-by-side, in the
bottom housing section 4 and protrude to the outside for the
purpose of establishing an electrical connection with an external
circuit (not shown).
The contacting end 1' of the switching element 1 is hemispherical,
allowing it to click-lock firmly in the position shown between the
two right-hand contact surfaces 2. The elastic force of the
diaphragm 5 pushes the switching element 1 against the contact
surfaces 2, resiliently holding it in that position.
Since the diaphragm 5 consists of an electrically nonconducting,
preferably thermoplastic material, the outside of the diaphragm 5
in the area of the free end of the switching element 1 can itself
serve as the actuating surface, obviating the need for a separate
actuating component in addition to the switching element 1.
The elastic force can be conveniently adjusted by means of notches
7 provided either on the outside or on the inside of the diaphragm
5, as shown in the illustration of the diaphragm in FIG. 4.
Depending on their size and number, these notches reduce the
elastic retractility of the diaphragm 5, thus allowing for a
certain selectability of the actuating force of the switch. The
notches may extend longitudinally or horizontally, depending on the
desired elastic effect.
The lateral movement of the switching element 1 is limited by the
rim of the recess 6' in the upper housing section 6. Accordingly,
the switching element 1 can only be shifted from the switch
position shown in FIG. 1 to the opposite switch position and back.
This establishes a reliable electrically conductive connection
between the central contact pin 3 and the corresponding left- or
right-hand outer contact pin 3.
The diaphragm 5 thus provides a hermetic seal protecting the
switching connections between the switching element 1 and the
contact surfaces 2 from the environment around the switch and thus
against contaminants and moisture.
The diaphragm 5 extends around the contact surfaces 2, thus also
serving as a seal between the bottom section 4 of the housing and
the top section 6 of the housing.
As an advantageous feature, the diaphragm 5 is firmly attached to
the outer section 6 of the housing as shown in the illustration.
This can be done for instance directly as part of the production
process or by subsequent installation in that position.
The lower section 4 of the housing, visible in the bottom view per
FIG. 2 and holding pre-installed contact pins 3, can be inserted
from the bottom and attached to the upper housing section 6 which
is already equipped with the diaphragm 5 and the switching element
1. The housing sections can be joined in conventional fashion
either permanently by cementing or welding them together or simply
by snapping them together via suitably shaped junction tabs or
strap joints. In either case, the electrical contact area within
the switch will be properly and reliably sealed.
FIG. 3 again shows a longitudinal section through the switch per
FIG. 1, in this case rotated 90.degree.. Here it can be seen, for
instance, that the three contact pins 3 are lined up one behind the
other in the bottom section 4 of the housing. It can also be seen
that the switching element 1 is preferably pin-shaped and
preferably in the form of a metal pin with a circular cross
section, with its outer surface constituted of the diaphragm 5.
This makes for a simple switching element of the switch assembly
that is pleasant to the touch and easy to operate.
In all of the illustrations the contact surfaces 2 are
hemispherical. However, they may also be designed differently, for
instance mushroom- or hook-shaped. Conceivably, mushroom-shaped
contact surfaces 2 could be used which on their part are
resiliently spring-mounted relative to, and in, the bottom section
4 of the housing, as illustrated in the drawings of FIGS. 5 and
6.
Instead of using three contact pins 3, it is equally possible to
install four contact pins 3 and contact surfaces 2, allowing not
only for two but for three different switch positions of the
switching element 1, as indicated in the diagram of FIG. 7. In FIG.
7 the switch is in the center position, electrically connecting the
two central contact surfaces 2 by way of the switching element 1.
Pushing the switching element 1 from this position to the left or
right will connect the two corresponding outer contact surfaces
2.
A substantial advantage of the design illustrated, apart from its
sealing properties, lies in the fact that even in comparison with
conventional switches it contains fewer parts, since the diaphragm
serves at once as a handle or actuator, a seal, and a spring that
applies the contacting force. The design presented also allows for
considerable miniaturization, whereby this switch is particularly
well suited to the integration in small, i.e. miniaturized,
electronic devices and especially in hearing aids, devices with
particularly heavy exposure to a moist, contaminant-containing
environment.
* * * * *